Mobile bulk material processing apparatus has been developed for a wide variety of applications including the processing of stone, minerals, construction materials and both domestic and industrial waste to generate smaller and/or size categorised aggregate for subsequent processing, use or disposal. For example, in both a quarry or clearance site environment, a mobile crusher is used to crush stone, rubble or site clearance material into smaller pieces. Typically, the crusher is provided with a hopper for receiving the bulk material and a discharge conveyor to transfer the processed and crushed material to a discharge location.
Mobile screening plants also utilise hoppers and discharge conveyors and function to separate the bulk material into one or more screened sized ranges e.g. sand, ballast and aggregate via a screen box unit. Both screening and crushing plants range in size to suit particular applications with smaller self-propelled screening and/or crushing plants being designed to be readily transportable from one site to another on for example a low loader or by being towed as a trailed vehicle. It is accordingly desirable for such processing plants to comprise operating components that can be readily adjusted between an operative (e.g. crushing or screening) mode and a transport mode. Accordingly, a number of mobile processing plants have been proposed having moving components that can be easily adjusted between deployed and transport positions without interfering with one another both in use and during transportation.
Example transportable processing plants with folding or pivoting operative components are described in WO 95/12462; EP 0506812; WO 97/41971; WO 02/26403; WO 2004/018106 and WO 2005/099903.
For most mobile processing plants, the discharge conveyor is one of the primary components that is required to be adaptable between the operating and transport positions. When operative, it is desirable for the conveyor to extend as far as possible from the main body of the plant to provide remote stockpiling of the processed material to the side or to the ends of the plant and to collapse to a compact configuration during transport. Typically, the conveyor is folded at a head and tail section to minimise the distance by which the conveyor projects from the main or central part of the plant (that typically carries the endless tracks or wheels). WO 02/26403 is a typical example of a stowed folded conveyor adapted for transportation between sites. However, the conveyor of conventional plants is exposed during transportation and is commonly damaged by contact with objects that may be propelled upward from the road (such as tyre debris) or project into the road (such as trees or other encroaching structures like bridges, lights, signs and the like). There is therefore a need for a mobile processing plant that addresses these problems.